xref: /openbmc/linux/crypto/rsa-pkcs1pad.c (revision ecfb9f40) 
1 // SPDX-License-Identifier: GPL-2.0-or-later
2 /*
3  * RSA padding templates.
4  *
5  * Copyright (c) 2015  Intel Corporation
6  */
7 
8 #include <crypto/algapi.h>
9 #include <crypto/akcipher.h>
10 #include <crypto/internal/akcipher.h>
11 #include <crypto/internal/rsa.h>
12 #include <linux/err.h>
13 #include <linux/init.h>
14 #include <linux/kernel.h>
15 #include <linux/module.h>
16 #include <linux/random.h>
17 #include <linux/scatterlist.h>
18 
19 /*
20  * Hash algorithm OIDs plus ASN.1 DER wrappings [RFC4880 sec 5.2.2].
21  */
22 static const u8 rsa_digest_info_md5[] = {
23 	0x30, 0x20, 0x30, 0x0c, 0x06, 0x08,
24 	0x2a, 0x86, 0x48, 0x86, 0xf7, 0x0d, 0x02, 0x05, /* OID */
25 	0x05, 0x00, 0x04, 0x10
26 };
27 
28 static const u8 rsa_digest_info_sha1[] = {
29 	0x30, 0x21, 0x30, 0x09, 0x06, 0x05,
30 	0x2b, 0x0e, 0x03, 0x02, 0x1a,
31 	0x05, 0x00, 0x04, 0x14
32 };
33 
34 static const u8 rsa_digest_info_rmd160[] = {
35 	0x30, 0x21, 0x30, 0x09, 0x06, 0x05,
36 	0x2b, 0x24, 0x03, 0x02, 0x01,
37 	0x05, 0x00, 0x04, 0x14
38 };
39 
40 static const u8 rsa_digest_info_sha224[] = {
41 	0x30, 0x2d, 0x30, 0x0d, 0x06, 0x09,
42 	0x60, 0x86, 0x48, 0x01, 0x65, 0x03, 0x04, 0x02, 0x04,
43 	0x05, 0x00, 0x04, 0x1c
44 };
45 
46 static const u8 rsa_digest_info_sha256[] = {
47 	0x30, 0x31, 0x30, 0x0d, 0x06, 0x09,
48 	0x60, 0x86, 0x48, 0x01, 0x65, 0x03, 0x04, 0x02, 0x01,
49 	0x05, 0x00, 0x04, 0x20
50 };
51 
52 static const u8 rsa_digest_info_sha384[] = {
53 	0x30, 0x41, 0x30, 0x0d, 0x06, 0x09,
54 	0x60, 0x86, 0x48, 0x01, 0x65, 0x03, 0x04, 0x02, 0x02,
55 	0x05, 0x00, 0x04, 0x30
56 };
57 
58 static const u8 rsa_digest_info_sha512[] = {
59 	0x30, 0x51, 0x30, 0x0d, 0x06, 0x09,
60 	0x60, 0x86, 0x48, 0x01, 0x65, 0x03, 0x04, 0x02, 0x03,
61 	0x05, 0x00, 0x04, 0x40
62 };
63 
64 static const struct rsa_asn1_template {
65 	const char	*name;
66 	const u8	*data;
67 	size_t		size;
68 } rsa_asn1_templates[] = {
69 #define _(X) { #X, rsa_digest_info_##X, sizeof(rsa_digest_info_##X) }
70 	_(md5),
71 	_(sha1),
72 	_(rmd160),
73 	_(sha256),
74 	_(sha384),
75 	_(sha512),
76 	_(sha224),
77 	{ NULL }
78 #undef _
79 };
80 
81 static const struct rsa_asn1_template *rsa_lookup_asn1(const char *name)
82 {
83 	const struct rsa_asn1_template *p;
84 
85 	for (p = rsa_asn1_templates; p->name; p++)
86 		if (strcmp(name, p->name) == 0)
87 			return p;
88 	return NULL;
89 }
90 
91 struct pkcs1pad_ctx {
92 	struct crypto_akcipher *child;
93 	unsigned int key_size;
94 };
95 
96 struct pkcs1pad_inst_ctx {
97 	struct crypto_akcipher_spawn spawn;
98 	const struct rsa_asn1_template *digest_info;
99 };
100 
101 struct pkcs1pad_request {
102 	struct scatterlist in_sg[2], out_sg[1];
103 	uint8_t *in_buf, *out_buf;
104 	struct akcipher_request child_req;
105 };
106 
107 static int pkcs1pad_set_pub_key(struct crypto_akcipher *tfm, const void *key,
108 		unsigned int keylen)
109 {
110 	struct pkcs1pad_ctx *ctx = akcipher_tfm_ctx(tfm);
111 	int err;
112 
113 	ctx->key_size = 0;
114 
115 	err = crypto_akcipher_set_pub_key(ctx->child, key, keylen);
116 	if (err)
117 		return err;
118 
119 	/* Find out new modulus size from rsa implementation */
120 	err = crypto_akcipher_maxsize(ctx->child);
121 	if (err > PAGE_SIZE)
122 		return -ENOTSUPP;
123 
124 	ctx->key_size = err;
125 	return 0;
126 }
127 
128 static int pkcs1pad_set_priv_key(struct crypto_akcipher *tfm, const void *key,
129 		unsigned int keylen)
130 {
131 	struct pkcs1pad_ctx *ctx = akcipher_tfm_ctx(tfm);
132 	int err;
133 
134 	ctx->key_size = 0;
135 
136 	err = crypto_akcipher_set_priv_key(ctx->child, key, keylen);
137 	if (err)
138 		return err;
139 
140 	/* Find out new modulus size from rsa implementation */
141 	err = crypto_akcipher_maxsize(ctx->child);
142 	if (err > PAGE_SIZE)
143 		return -ENOTSUPP;
144 
145 	ctx->key_size = err;
146 	return 0;
147 }
148 
149 static unsigned int pkcs1pad_get_max_size(struct crypto_akcipher *tfm)
150 {
151 	struct pkcs1pad_ctx *ctx = akcipher_tfm_ctx(tfm);
152 
153 	/*
154 	 * The maximum destination buffer size for the encrypt/sign operations
155 	 * will be the same as for RSA, even though it's smaller for
156 	 * decrypt/verify.
157 	 */
158 
159 	return ctx->key_size;
160 }
161 
162 static void pkcs1pad_sg_set_buf(struct scatterlist *sg, void *buf, size_t len,
163 		struct scatterlist *next)
164 {
165 	int nsegs = next ? 2 : 1;
166 
167 	sg_init_table(sg, nsegs);
168 	sg_set_buf(sg, buf, len);
169 
170 	if (next)
171 		sg_chain(sg, nsegs, next);
172 }
173 
174 static int pkcs1pad_encrypt_sign_complete(struct akcipher_request *req, int err)
175 {
176 	struct crypto_akcipher *tfm = crypto_akcipher_reqtfm(req);
177 	struct pkcs1pad_ctx *ctx = akcipher_tfm_ctx(tfm);
178 	struct pkcs1pad_request *req_ctx = akcipher_request_ctx(req);
179 	unsigned int pad_len;
180 	unsigned int len;
181 	u8 *out_buf;
182 
183 	if (err)
184 		goto out;
185 
186 	len = req_ctx->child_req.dst_len;
187 	pad_len = ctx->key_size - len;
188 
189 	/* Four billion to one */
190 	if (likely(!pad_len))
191 		goto out;
192 
193 	out_buf = kzalloc(ctx->key_size, GFP_KERNEL);
194 	err = -ENOMEM;
195 	if (!out_buf)
196 		goto out;
197 
198 	sg_copy_to_buffer(req->dst, sg_nents_for_len(req->dst, len),
199 			  out_buf + pad_len, len);
200 	sg_copy_from_buffer(req->dst,
201 			    sg_nents_for_len(req->dst, ctx->key_size),
202 			    out_buf, ctx->key_size);
203 	kfree_sensitive(out_buf);
204 
205 out:
206 	req->dst_len = ctx->key_size;
207 
208 	kfree(req_ctx->in_buf);
209 
210 	return err;
211 }
212 
213 static void pkcs1pad_encrypt_sign_complete_cb(
214 		struct crypto_async_request *child_async_req, int err)
215 {
216 	struct akcipher_request *req = child_async_req->data;
217 	struct crypto_async_request async_req;
218 
219 	if (err == -EINPROGRESS)
220 		return;
221 
222 	async_req.data = req->base.data;
223 	async_req.tfm = crypto_akcipher_tfm(crypto_akcipher_reqtfm(req));
224 	async_req.flags = child_async_req->flags;
225 	req->base.complete(&async_req,
226 			pkcs1pad_encrypt_sign_complete(req, err));
227 }
228 
229 static int pkcs1pad_encrypt(struct akcipher_request *req)
230 {
231 	struct crypto_akcipher *tfm = crypto_akcipher_reqtfm(req);
232 	struct pkcs1pad_ctx *ctx = akcipher_tfm_ctx(tfm);
233 	struct pkcs1pad_request *req_ctx = akcipher_request_ctx(req);
234 	int err;
235 	unsigned int i, ps_end;
236 
237 	if (!ctx->key_size)
238 		return -EINVAL;
239 
240 	if (req->src_len > ctx->key_size - 11)
241 		return -EOVERFLOW;
242 
243 	if (req->dst_len < ctx->key_size) {
244 		req->dst_len = ctx->key_size;
245 		return -EOVERFLOW;
246 	}
247 
248 	req_ctx->in_buf = kmalloc(ctx->key_size - 1 - req->src_len,
249 				  GFP_KERNEL);
250 	if (!req_ctx->in_buf)
251 		return -ENOMEM;
252 
253 	ps_end = ctx->key_size - req->src_len - 2;
254 	req_ctx->in_buf[0] = 0x02;
255 	for (i = 1; i < ps_end; i++)
256 		req_ctx->in_buf[i] = get_random_u32_inclusive(1, 255);
257 	req_ctx->in_buf[ps_end] = 0x00;
258 
259 	pkcs1pad_sg_set_buf(req_ctx->in_sg, req_ctx->in_buf,
260 			ctx->key_size - 1 - req->src_len, req->src);
261 
262 	akcipher_request_set_tfm(&req_ctx->child_req, ctx->child);
263 	akcipher_request_set_callback(&req_ctx->child_req, req->base.flags,
264 			pkcs1pad_encrypt_sign_complete_cb, req);
265 
266 	/* Reuse output buffer */
267 	akcipher_request_set_crypt(&req_ctx->child_req, req_ctx->in_sg,
268 				   req->dst, ctx->key_size - 1, req->dst_len);
269 
270 	err = crypto_akcipher_encrypt(&req_ctx->child_req);
271 	if (err != -EINPROGRESS && err != -EBUSY)
272 		return pkcs1pad_encrypt_sign_complete(req, err);
273 
274 	return err;
275 }
276 
277 static int pkcs1pad_decrypt_complete(struct akcipher_request *req, int err)
278 {
279 	struct crypto_akcipher *tfm = crypto_akcipher_reqtfm(req);
280 	struct pkcs1pad_ctx *ctx = akcipher_tfm_ctx(tfm);
281 	struct pkcs1pad_request *req_ctx = akcipher_request_ctx(req);
282 	unsigned int dst_len;
283 	unsigned int pos;
284 	u8 *out_buf;
285 
286 	if (err)
287 		goto done;
288 
289 	err = -EINVAL;
290 	dst_len = req_ctx->child_req.dst_len;
291 	if (dst_len < ctx->key_size - 1)
292 		goto done;
293 
294 	out_buf = req_ctx->out_buf;
295 	if (dst_len == ctx->key_size) {
296 		if (out_buf[0] != 0x00)
297 			/* Decrypted value had no leading 0 byte */
298 			goto done;
299 
300 		dst_len--;
301 		out_buf++;
302 	}
303 
304 	if (out_buf[0] != 0x02)
305 		goto done;
306 
307 	for (pos = 1; pos < dst_len; pos++)
308 		if (out_buf[pos] == 0x00)
309 			break;
310 	if (pos < 9 || pos == dst_len)
311 		goto done;
312 	pos++;
313 
314 	err = 0;
315 
316 	if (req->dst_len < dst_len - pos)
317 		err = -EOVERFLOW;
318 	req->dst_len = dst_len - pos;
319 
320 	if (!err)
321 		sg_copy_from_buffer(req->dst,
322 				sg_nents_for_len(req->dst, req->dst_len),
323 				out_buf + pos, req->dst_len);
324 
325 done:
326 	kfree_sensitive(req_ctx->out_buf);
327 
328 	return err;
329 }
330 
331 static void pkcs1pad_decrypt_complete_cb(
332 		struct crypto_async_request *child_async_req, int err)
333 {
334 	struct akcipher_request *req = child_async_req->data;
335 	struct crypto_async_request async_req;
336 
337 	if (err == -EINPROGRESS)
338 		return;
339 
340 	async_req.data = req->base.data;
341 	async_req.tfm = crypto_akcipher_tfm(crypto_akcipher_reqtfm(req));
342 	async_req.flags = child_async_req->flags;
343 	req->base.complete(&async_req, pkcs1pad_decrypt_complete(req, err));
344 }
345 
346 static int pkcs1pad_decrypt(struct akcipher_request *req)
347 {
348 	struct crypto_akcipher *tfm = crypto_akcipher_reqtfm(req);
349 	struct pkcs1pad_ctx *ctx = akcipher_tfm_ctx(tfm);
350 	struct pkcs1pad_request *req_ctx = akcipher_request_ctx(req);
351 	int err;
352 
353 	if (!ctx->key_size || req->src_len != ctx->key_size)
354 		return -EINVAL;
355 
356 	req_ctx->out_buf = kmalloc(ctx->key_size, GFP_KERNEL);
357 	if (!req_ctx->out_buf)
358 		return -ENOMEM;
359 
360 	pkcs1pad_sg_set_buf(req_ctx->out_sg, req_ctx->out_buf,
361 			    ctx->key_size, NULL);
362 
363 	akcipher_request_set_tfm(&req_ctx->child_req, ctx->child);
364 	akcipher_request_set_callback(&req_ctx->child_req, req->base.flags,
365 			pkcs1pad_decrypt_complete_cb, req);
366 
367 	/* Reuse input buffer, output to a new buffer */
368 	akcipher_request_set_crypt(&req_ctx->child_req, req->src,
369 				   req_ctx->out_sg, req->src_len,
370 				   ctx->key_size);
371 
372 	err = crypto_akcipher_decrypt(&req_ctx->child_req);
373 	if (err != -EINPROGRESS && err != -EBUSY)
374 		return pkcs1pad_decrypt_complete(req, err);
375 
376 	return err;
377 }
378 
379 static int pkcs1pad_sign(struct akcipher_request *req)
380 {
381 	struct crypto_akcipher *tfm = crypto_akcipher_reqtfm(req);
382 	struct pkcs1pad_ctx *ctx = akcipher_tfm_ctx(tfm);
383 	struct pkcs1pad_request *req_ctx = akcipher_request_ctx(req);
384 	struct akcipher_instance *inst = akcipher_alg_instance(tfm);
385 	struct pkcs1pad_inst_ctx *ictx = akcipher_instance_ctx(inst);
386 	const struct rsa_asn1_template *digest_info = ictx->digest_info;
387 	int err;
388 	unsigned int ps_end, digest_info_size = 0;
389 
390 	if (!ctx->key_size)
391 		return -EINVAL;
392 
393 	if (digest_info)
394 		digest_info_size = digest_info->size;
395 
396 	if (req->src_len + digest_info_size > ctx->key_size - 11)
397 		return -EOVERFLOW;
398 
399 	if (req->dst_len < ctx->key_size) {
400 		req->dst_len = ctx->key_size;
401 		return -EOVERFLOW;
402 	}
403 
404 	req_ctx->in_buf = kmalloc(ctx->key_size - 1 - req->src_len,
405 				  GFP_KERNEL);
406 	if (!req_ctx->in_buf)
407 		return -ENOMEM;
408 
409 	ps_end = ctx->key_size - digest_info_size - req->src_len - 2;
410 	req_ctx->in_buf[0] = 0x01;
411 	memset(req_ctx->in_buf + 1, 0xff, ps_end - 1);
412 	req_ctx->in_buf[ps_end] = 0x00;
413 
414 	if (digest_info)
415 		memcpy(req_ctx->in_buf + ps_end + 1, digest_info->data,
416 		       digest_info->size);
417 
418 	pkcs1pad_sg_set_buf(req_ctx->in_sg, req_ctx->in_buf,
419 			ctx->key_size - 1 - req->src_len, req->src);
420 
421 	akcipher_request_set_tfm(&req_ctx->child_req, ctx->child);
422 	akcipher_request_set_callback(&req_ctx->child_req, req->base.flags,
423 			pkcs1pad_encrypt_sign_complete_cb, req);
424 
425 	/* Reuse output buffer */
426 	akcipher_request_set_crypt(&req_ctx->child_req, req_ctx->in_sg,
427 				   req->dst, ctx->key_size - 1, req->dst_len);
428 
429 	err = crypto_akcipher_decrypt(&req_ctx->child_req);
430 	if (err != -EINPROGRESS && err != -EBUSY)
431 		return pkcs1pad_encrypt_sign_complete(req, err);
432 
433 	return err;
434 }
435 
436 static int pkcs1pad_verify_complete(struct akcipher_request *req, int err)
437 {
438 	struct crypto_akcipher *tfm = crypto_akcipher_reqtfm(req);
439 	struct pkcs1pad_ctx *ctx = akcipher_tfm_ctx(tfm);
440 	struct pkcs1pad_request *req_ctx = akcipher_request_ctx(req);
441 	struct akcipher_instance *inst = akcipher_alg_instance(tfm);
442 	struct pkcs1pad_inst_ctx *ictx = akcipher_instance_ctx(inst);
443 	const struct rsa_asn1_template *digest_info = ictx->digest_info;
444 	const unsigned int sig_size = req->src_len;
445 	const unsigned int digest_size = req->dst_len;
446 	unsigned int dst_len;
447 	unsigned int pos;
448 	u8 *out_buf;
449 
450 	if (err)
451 		goto done;
452 
453 	err = -EINVAL;
454 	dst_len = req_ctx->child_req.dst_len;
455 	if (dst_len < ctx->key_size - 1)
456 		goto done;
457 
458 	out_buf = req_ctx->out_buf;
459 	if (dst_len == ctx->key_size) {
460 		if (out_buf[0] != 0x00)
461 			/* Decrypted value had no leading 0 byte */
462 			goto done;
463 
464 		dst_len--;
465 		out_buf++;
466 	}
467 
468 	err = -EBADMSG;
469 	if (out_buf[0] != 0x01)
470 		goto done;
471 
472 	for (pos = 1; pos < dst_len; pos++)
473 		if (out_buf[pos] != 0xff)
474 			break;
475 
476 	if (pos < 9 || pos == dst_len || out_buf[pos] != 0x00)
477 		goto done;
478 	pos++;
479 
480 	if (digest_info) {
481 		if (digest_info->size > dst_len - pos)
482 			goto done;
483 		if (crypto_memneq(out_buf + pos, digest_info->data,
484 				  digest_info->size))
485 			goto done;
486 
487 		pos += digest_info->size;
488 	}
489 
490 	err = 0;
491 
492 	if (digest_size != dst_len - pos) {
493 		err = -EKEYREJECTED;
494 		req->dst_len = dst_len - pos;
495 		goto done;
496 	}
497 	/* Extract appended digest. */
498 	sg_pcopy_to_buffer(req->src,
499 			   sg_nents_for_len(req->src, sig_size + digest_size),
500 			   req_ctx->out_buf + ctx->key_size,
501 			   digest_size, sig_size);
502 	/* Do the actual verification step. */
503 	if (memcmp(req_ctx->out_buf + ctx->key_size, out_buf + pos,
504 		   digest_size) != 0)
505 		err = -EKEYREJECTED;
506 done:
507 	kfree_sensitive(req_ctx->out_buf);
508 
509 	return err;
510 }
511 
512 static void pkcs1pad_verify_complete_cb(
513 		struct crypto_async_request *child_async_req, int err)
514 {
515 	struct akcipher_request *req = child_async_req->data;
516 	struct crypto_async_request async_req;
517 
518 	if (err == -EINPROGRESS)
519 		return;
520 
521 	async_req.data = req->base.data;
522 	async_req.tfm = crypto_akcipher_tfm(crypto_akcipher_reqtfm(req));
523 	async_req.flags = child_async_req->flags;
524 	req->base.complete(&async_req, pkcs1pad_verify_complete(req, err));
525 }
526 
527 /*
528  * The verify operation is here for completeness similar to the verification
529  * defined in RFC2313 section 10.2 except that block type 0 is not accepted,
530  * as in RFC2437.  RFC2437 section 9.2 doesn't define any operation to
531  * retrieve the DigestInfo from a signature, instead the user is expected
532  * to call the sign operation to generate the expected signature and compare
533  * signatures instead of the message-digests.
534  */
535 static int pkcs1pad_verify(struct akcipher_request *req)
536 {
537 	struct crypto_akcipher *tfm = crypto_akcipher_reqtfm(req);
538 	struct pkcs1pad_ctx *ctx = akcipher_tfm_ctx(tfm);
539 	struct pkcs1pad_request *req_ctx = akcipher_request_ctx(req);
540 	const unsigned int sig_size = req->src_len;
541 	const unsigned int digest_size = req->dst_len;
542 	int err;
543 
544 	if (WARN_ON(req->dst) || WARN_ON(!digest_size) ||
545 	    !ctx->key_size || sig_size != ctx->key_size)
546 		return -EINVAL;
547 
548 	req_ctx->out_buf = kmalloc(ctx->key_size + digest_size, GFP_KERNEL);
549 	if (!req_ctx->out_buf)
550 		return -ENOMEM;
551 
552 	pkcs1pad_sg_set_buf(req_ctx->out_sg, req_ctx->out_buf,
553 			    ctx->key_size, NULL);
554 
555 	akcipher_request_set_tfm(&req_ctx->child_req, ctx->child);
556 	akcipher_request_set_callback(&req_ctx->child_req, req->base.flags,
557 			pkcs1pad_verify_complete_cb, req);
558 
559 	/* Reuse input buffer, output to a new buffer */
560 	akcipher_request_set_crypt(&req_ctx->child_req, req->src,
561 				   req_ctx->out_sg, sig_size, ctx->key_size);
562 
563 	err = crypto_akcipher_encrypt(&req_ctx->child_req);
564 	if (err != -EINPROGRESS && err != -EBUSY)
565 		return pkcs1pad_verify_complete(req, err);
566 
567 	return err;
568 }
569 
570 static int pkcs1pad_init_tfm(struct crypto_akcipher *tfm)
571 {
572 	struct akcipher_instance *inst = akcipher_alg_instance(tfm);
573 	struct pkcs1pad_inst_ctx *ictx = akcipher_instance_ctx(inst);
574 	struct pkcs1pad_ctx *ctx = akcipher_tfm_ctx(tfm);
575 	struct crypto_akcipher *child_tfm;
576 
577 	child_tfm = crypto_spawn_akcipher(&ictx->spawn);
578 	if (IS_ERR(child_tfm))
579 		return PTR_ERR(child_tfm);
580 
581 	ctx->child = child_tfm;
582 
583 	akcipher_set_reqsize(tfm, sizeof(struct pkcs1pad_request) +
584 				  crypto_akcipher_reqsize(child_tfm));
585 
586 	return 0;
587 }
588 
589 static void pkcs1pad_exit_tfm(struct crypto_akcipher *tfm)
590 {
591 	struct pkcs1pad_ctx *ctx = akcipher_tfm_ctx(tfm);
592 
593 	crypto_free_akcipher(ctx->child);
594 }
595 
596 static void pkcs1pad_free(struct akcipher_instance *inst)
597 {
598 	struct pkcs1pad_inst_ctx *ctx = akcipher_instance_ctx(inst);
599 	struct crypto_akcipher_spawn *spawn = &ctx->spawn;
600 
601 	crypto_drop_akcipher(spawn);
602 	kfree(inst);
603 }
604 
605 static int pkcs1pad_create(struct crypto_template *tmpl, struct rtattr **tb)
606 {
607 	u32 mask;
608 	struct akcipher_instance *inst;
609 	struct pkcs1pad_inst_ctx *ctx;
610 	struct akcipher_alg *rsa_alg;
611 	const char *hash_name;
612 	int err;
613 
614 	err = crypto_check_attr_type(tb, CRYPTO_ALG_TYPE_AKCIPHER, &mask);
615 	if (err)
616 		return err;
617 
618 	inst = kzalloc(sizeof(*inst) + sizeof(*ctx), GFP_KERNEL);
619 	if (!inst)
620 		return -ENOMEM;
621 
622 	ctx = akcipher_instance_ctx(inst);
623 
624 	err = crypto_grab_akcipher(&ctx->spawn, akcipher_crypto_instance(inst),
625 				   crypto_attr_alg_name(tb[1]), 0, mask);
626 	if (err)
627 		goto err_free_inst;
628 
629 	rsa_alg = crypto_spawn_akcipher_alg(&ctx->spawn);
630 
631 	if (strcmp(rsa_alg->base.cra_name, "rsa") != 0) {
632 		err = -EINVAL;
633 		goto err_free_inst;
634 	}
635 
636 	err = -ENAMETOOLONG;
637 	hash_name = crypto_attr_alg_name(tb[2]);
638 	if (IS_ERR(hash_name)) {
639 		if (snprintf(inst->alg.base.cra_name,
640 			     CRYPTO_MAX_ALG_NAME, "pkcs1pad(%s)",
641 			     rsa_alg->base.cra_name) >= CRYPTO_MAX_ALG_NAME)
642 			goto err_free_inst;
643 
644 		if (snprintf(inst->alg.base.cra_driver_name,
645 			     CRYPTO_MAX_ALG_NAME, "pkcs1pad(%s)",
646 			     rsa_alg->base.cra_driver_name) >=
647 			     CRYPTO_MAX_ALG_NAME)
648 			goto err_free_inst;
649 	} else {
650 		ctx->digest_info = rsa_lookup_asn1(hash_name);
651 		if (!ctx->digest_info) {
652 			err = -EINVAL;
653 			goto err_free_inst;
654 		}
655 
656 		if (snprintf(inst->alg.base.cra_name, CRYPTO_MAX_ALG_NAME,
657 			     "pkcs1pad(%s,%s)", rsa_alg->base.cra_name,
658 			     hash_name) >= CRYPTO_MAX_ALG_NAME)
659 			goto err_free_inst;
660 
661 		if (snprintf(inst->alg.base.cra_driver_name,
662 			     CRYPTO_MAX_ALG_NAME, "pkcs1pad(%s,%s)",
663 			     rsa_alg->base.cra_driver_name,
664 			     hash_name) >= CRYPTO_MAX_ALG_NAME)
665 			goto err_free_inst;
666 	}
667 
668 	inst->alg.base.cra_priority = rsa_alg->base.cra_priority;
669 	inst->alg.base.cra_ctxsize = sizeof(struct pkcs1pad_ctx);
670 
671 	inst->alg.init = pkcs1pad_init_tfm;
672 	inst->alg.exit = pkcs1pad_exit_tfm;
673 
674 	inst->alg.encrypt = pkcs1pad_encrypt;
675 	inst->alg.decrypt = pkcs1pad_decrypt;
676 	inst->alg.sign = pkcs1pad_sign;
677 	inst->alg.verify = pkcs1pad_verify;
678 	inst->alg.set_pub_key = pkcs1pad_set_pub_key;
679 	inst->alg.set_priv_key = pkcs1pad_set_priv_key;
680 	inst->alg.max_size = pkcs1pad_get_max_size;
681 
682 	inst->free = pkcs1pad_free;
683 
684 	err = akcipher_register_instance(tmpl, inst);
685 	if (err) {
686 err_free_inst:
687 		pkcs1pad_free(inst);
688 	}
689 	return err;
690 }
691 
692 struct crypto_template rsa_pkcs1pad_tmpl = {
693 	.name = "pkcs1pad",
694 	.create = pkcs1pad_create,
695 	.module = THIS_MODULE,
696 };
697